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- /* IEEE754 floating point arithmetic
- * double precision: common utilities
- */
- /*
- * MIPS floating point support
- * Copyright (C) 1994-2000 Algorithmics Ltd.
- *
- * This program is free software; you can distribute it and/or modify it
- * under the terms of the GNU General Public License (Version 2) as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
- * for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- */
- #include "ieee754dp.h"
- union ieee754dp ieee754dp_add(union ieee754dp x, union ieee754dp y)
- {
- int s;
- COMPXDP;
- COMPYDP;
- EXPLODEXDP;
- EXPLODEYDP;
- ieee754_clearcx();
- FLUSHXDP;
- FLUSHYDP;
- switch (CLPAIR(xc, yc)) {
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
- return ieee754dp_nanxcpt(y);
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
- case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
- return ieee754dp_nanxcpt(x);
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
- return y;
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
- case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
- return x;
- /*
- * Infinity handling
- */
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
- if (xs == ys)
- return x;
- ieee754_setcx(IEEE754_INVALID_OPERATION);
- return ieee754dp_indef();
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
- return y;
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
- case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
- return x;
- /*
- * Zero handling
- */
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
- if (xs == ys)
- return x;
- else
- return ieee754dp_zero(ieee754_csr.rm == FPU_CSR_RD);
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
- return x;
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
- case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
- return y;
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
- DPDNORMX;
- /* FALL THROUGH */
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
- DPDNORMY;
- break;
- case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
- DPDNORMX;
- break;
- case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
- break;
- }
- assert(xm & DP_HIDDEN_BIT);
- assert(ym & DP_HIDDEN_BIT);
- /*
- * Provide guard,round and stick bit space.
- */
- xm <<= 3;
- ym <<= 3;
- if (xe > ye) {
- /*
- * Have to shift y fraction right to align.
- */
- s = xe - ye;
- ym = XDPSRS(ym, s);
- ye += s;
- } else if (ye > xe) {
- /*
- * Have to shift x fraction right to align.
- */
- s = ye - xe;
- xm = XDPSRS(xm, s);
- xe += s;
- }
- assert(xe == ye);
- assert(xe <= DP_EMAX);
- if (xs == ys) {
- /*
- * Generate 28 bit result of adding two 27 bit numbers
- * leaving result in xm, xs and xe.
- */
- xm = xm + ym;
- if (xm >> (DP_FBITS + 1 + 3)) { /* carry out */
- xm = XDPSRS1(xm);
- xe++;
- }
- } else {
- if (xm >= ym) {
- xm = xm - ym;
- } else {
- xm = ym - xm;
- xs = ys;
- }
- if (xm == 0)
- return ieee754dp_zero(ieee754_csr.rm == FPU_CSR_RD);
- /*
- * Normalize to rounding precision.
- */
- while ((xm >> (DP_FBITS + 3)) == 0) {
- xm <<= 1;
- xe--;
- }
- }
- return ieee754dp_format(xs, xe, xm);
- }
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